Flow charts could describe accounting machines as well as computers. This clear plastic rule is colored white around the edges. It has a grid of lines drawn in the background, with twelve symbols cut out. Across the top is a scale for 402-403 type bar spacing. Across the bottom are scales of mark sensing and card column numbers. Along the left is a scale of line spaces. Along the right is a scale of punching positions. The IBM 402 and IBM 403 were IBM accounting machines that sold from the late 1940s into the mid-1960s.
Our collection database is a work in progress. We may update this record based on further research and review. Learn more about our approach to sharing our collection online.